1. Field of the Invention
This invention relates to a complex material, artificial light-emitting skin and artificial light-emitting body that are suitable for use, for example, in the field of entertainment or amusement using emission of light effectively.
2. Description of the Related Art
For years, aluminate compound materials doped with rare earth elements have been remarked as fluorescent materials, and have been under vigorous researches. Among various aluminate compound materials, Eu-doped SrAl2O4 (named SrAl2O4:Eu herein below) has attracted the greatest attention as from a report on the phenomenon of stress emission as introduced herein below. Thus, prehistory of researches and developments of this SrAl2O4:Eu is first explained below while citing prior art documents.
History of Patents and Researches of SrAl2O4:Eu as Fluorescent Material
SrAl2O4:Eu has the prehistory of having been studies as a fluorescent material from a long time ago. U.S. Pat. No. 3,294,699 on this material issued already in the 1960s, and the material is currently one of known materials.
History of Inventions and Researches of Phosphorescent Material/Long-afterglow Phosphor SrAl2O4:Eu+Dy (Brand Name “LumiNova”) by Nemoto & Co., Ltd.
There are many reports and commentaries on this phosphor, some of which are listed below.
Non-patent Document 1:
    URL: http://www/nemoto.co.jp/index_j.html accessed through the Internet on Aug. 30, 2002Non-Patent Document 2:    URL: http://www/nemoto.co.jp/products/luminova/index.html accessed through the Internet on Aug. 30, 2002Non-Patent Document 3:    URL: http://www/nemoto.co.jp/product/01_luminova/index.html accessed through the Internet on Aug. 30, 2002Non-Patent Document 4:    URL: http://www/nemoto.co.jp/column/10_glow.html accessed through the Internet on Aug. 30, 2002Patent Document 2:    Specification of Japanese Patent No. 2543825Patent Document 3:    Specification of U.S. Pat. No. 5,424,006Patent Document 4:    Specification of European Patent No. 622440Non-patent Document 5:    T. Matsuzawa, N. Takeuchi, Y. Aoki and Y. Murakami, 248th Lecture Papers of Phosphor Research Society “Proc. Phosphor Res. Soc.” (1993 Nov. 26) 7-13Non-patent Document 6:    Yoshihiko Murakami, Nikkei Science, 5(1996) 20-29Non-patent Document 7:    T. Matsuzawa, Y. Aoki, T. Takeuchi and Y. Murayama, J. Electrochem. Soc., 143(1996) 2670-2673Non-patent Document 8:    Ceramics, 32(1997) 40-43Non-patent Document 9:    Y. Murakami, Hakaru, 42(1997) 2-7Discovery of Stress Emission in SrAl2O4:Eu Compound Materials by C- N. Xu, et al. of National Institute of Advanced Industrial Science and Technology (AIST), Institute for Structural and Engineering Materials (ISEM), Multifunctional Materials Technology Group (Former, MITI Institute for Industrial Technology, Kyushu Institute for Industry and Technology, Laboratory for Inorganic Complex Materials and Functional Ceramics) as well as History of Related Patents and Researches
There are many commentaries and reports on the stress emission SrAl2O4:Eu compound materials and related substances, such as, for example, Non-patent Documents 10-17 and Patent Documents 5-19 that are listed below.
Non-patent Document 10: C- N. Xu, AIST Today, vol. 2, No. 8 (2002)
Non-patent Document 11: URL:
    http//www.aist.go.jp/aist13 j/aistinfo/aist_today/vol02—08/vol02—80_main.html accessed through the Internet on Aug. 30, 2002Non-patent Document 12: URL:    http//www.aist.go.jp/aist_j/aistinfo/aist_today/vol02—08/vol02—08_p13.pdf accessed through the Internet on Aug. 30, 2002Non-patent Document 13: C- N. Xu, T. Watanabe, M. Akiyama and X- G. Zheng, Appl. Phys. Lett., 74(1999) 1236-1238Non-patent Document 14: C- N. Xu, T. Watanabe, M. Akiyama and X- G. Zheng, Appl. Phys. Lett., 74(1999) 2414-2416Non-patent Document 15: C- N. Xu, X- G Zheng, M. Akiyama, K. Nonaka and T. Watanabe, Appl. Phys. Lett., 76(2000)179-181Non-patent Document 16: C- N. Xu, Kagaku Kogyo (October 2000) pp. 790-794 & 808Non-patent Document 17: C- N. Xu, Gekkan Display, September (2001) 98-103Patent Document 5: Japanese Laid-open Publication JP-1999-116946-APatent Document 6: Specification of Japanese Patent No. 3265356Patent Document 7: Specification of Japanese Patent No. 3136340Patent Document 8: Specification of Japanese Patent No. 3136338Patent Document 9: Specification of Japanese Patent No. 2992631Patent Document 10: Japanese Patent Laid-open Publication JP-2000-313878-APatent Document 11: Japanese Patent Laid-open Publication JP-2001-49251-APatent Document 12: Japanese Patent Laid-open Publication JP-2001-123162-APatent Document 13: Japanese Patent Laid-open Publication JP-2001-215157-APatent Document 14: Specification of Japanese Patent No. 3273317Patent Document 15: Japanese Patent Laid-open Publication JP-2002-194349-APatent Document 16: Japanese Patent Laid-open Publication JP-2002-194350-APatent Document 17: Japanese Patent Laid-open Publication JP-2002-201068-APatent Document 17: Specification of U.S. Pat. No. 6,117,574Patent Document 18: Specification of U.S. Pat. No. 6,159,394
Patent Document 5 discloses materials that contain 0.01˜20 weight percent of rare earths or transition metals and emit light with external mechanical energy received by a wurzite type piezoelectric material. Patent Document 6 discloses thin films of these materials. Patent Document 7 discloses materials that contain transition elements or rare earth elements having electron shells of 3d, 4d, 5d and 4f added to MgAl2O4, CaAl2O4, Al2O3 and SrMgAl10O17 as their matrices and emit light upon deformation with a mechanical external force, as well as a manufacturing method thereof. Patent Document 8 discloses materials that are made of substances containing transition elements or rare earth elements having electron shells of 3d, 4d, 5d and 4f and added to matrix crystals of metal oxides/complex oxides, and emit light by mechanical deformation. Patent Document 9 discloses materials containing transition elements or rare earths added to matrix materials of Sr3Al2O6 and Ga3Al2O6, as well as a manufacturing method thereof by baking under a controlled amount of the additive substance in 0.01˜20 weight percent in a reducing atmosphere adjusted to 800-1700° C. Patent Document 10 discloses materials containing rare earths or transition metal elements as emission centers added to matrix materials of Y-Ba-Mg-Si oxides, which convert external mechanical energy to light. Patent Document 11 describes materials that contain regulated aluminate having a non-stoichiometrical composition and emit light under mechanical energy. Patent Document 12 describes mMO.nAl2O3 materials as phosphorus memory excited by visible light. Patent Document 13 discloses a system for measuring the stress profile by using a stress emission material. Patent Document 14 discloses materials that contain oxides having a melilite type crystal structure (such as CaYAl2O7, Ca2Al2SiO7 or the like) as their matrices and emit light under mechanical energy. Patent Document 15 discloses materials MN2O4, where M=Mg, Sr, Ba or Zn, N=Ga or Al, doped with rare earths or transition metals as their emission centers, together with a manufacturing method thereof. Patent Document 16 describes field emission materials composed of aluminate as their matrices and containing doped rare earths or transition elements. Patent Document 17 discloses electrostriction materials of (Sr, Ba, Mg, Ca, Zn, Cd)−(Al, Ga, Si) oxides having the maximum distortion of 1%. This is a considerably large value. Patent Document 18 discloses piezoelectric materials among triboluminescent materials. Patent Document 19 mainly describes Sr3Al3O6 among stress emission materials, and this document corresponds to Patent Document 9.
Next explained are prior art technologies for complexing stress emission substances, mainly SrAl2O3, and resins.
Products incorporating complex materials commercially named “LumiNova” (SrAl2O4:Eu+Dy) into resins are on sale in form of “incorporated resin pellets” from Nemoto & Co., Ltd. They are introduced in the web sites, URL: http://www.nemoto.co.jp/products/luminova/index.html accessed through the Internet on Aug. 30, 2002 and herein taken as Non-patent Document 18, and URL: http://www.nemoto.co.jp/products/gss/index.html accessed through the Internet on Aug. 30, 2002 and herein taken as Non-patent Document 19.
The above web documents and Non-patent Document 9 disclose polymethylmethacrylate (PMMA), ABS resins, polycarbonate (PC), polystyrene (PS), Polyethylene (PE), polypropylene (PP), polyacetals (PA) and urethane resins as resin materials. Further, according to the web documents, there seems to be a trial of incorporation into silicone rubber. However, no details are disclosed. About mixture ratios of powder and resins, it is only taught that is the sole disclosure that it is around 10% in weight ratio.
On the other hand, most of complex materials reported in research papers of the discoverer of stress emission, Xu, and others, are mixtures of powder into epoxy resins as matrices, and they are in form of bulk agglomerates. Therefore, strong mechanical force from a vise, for example, is required to induce their emission of light.
In Non-patent Document 10, Xu describes application of his complex materials mainly to technologies for visualizing stress profiles and various types of displays. However, he describes or suggests nothing about development of their applications to artificial light-emitting skins, artificial light-emitting bodies, and the like, for the purpose of entertainment. Additionally, concerning complexing techniques, the sole statement is found in a research paper about epoxy resin molding. Complexing with other resins is not found at all in the web documents either.
As application products of phosphorescent materials developed by Nemoto & Co., Ltd., heretofore known are products from Tokyo Intelligent Network Kabushiki Kaisha (Non-patent Document 20: URL: http://www2.raidway.ne.jp˜tin/ accessed through the Internet on Aug. 30, 2002, and Non-patent Document 21: URL: http://www2.raidway.ne.jp/˜tin/nl/nl.html accessed through the Internet on Aug. 30, 2002), and products from San Unit Company (Non-patent Document 22: URL: http://web.kyoto-inet.or.jp/people/sansanuc/s4.html accessed through the Internet on Aug. 30, 2002). Non-patent documents 20, 21 demonstrate phosphorescent tiles, phosphorescent straps, phosphorescent special make gel, phosphorescent wallpaper, and so on, as applications of phosphorescent materials. Non-patent document 22 demonstrates applications of phosphorescent materials to tiles, paints, pellets, balls, and so on. However, there is no disclosure or suggestion on developments of applications to artificial light-emitting skins, artificial light-emitting bodies, and the like, for the purpose of entertainment.
Patent Document 20 (Japanese Patent Laid-open Publication JP-1997-95671-A) has no description on stress emission, but proposes transparent phosphorescent materials prepared by using transparent substrates such as glass plates, resin plates, films, and so on, and dispersing therein ultrafine particulate long afterglow inorganic phosphors such as SrAl2O4:Eu.
Complex materials or sheet-like molded products obtained by the above-introduced and other conventional complexing techniques are too hard for a person to bring about stress emission easily with their own force. Moreover, since the above-mentioned resin-incorporated materials have long afterglow properties, they undesirably appear always luminous, and are difficult to appear luminous only with a touch, for example. Therefore, they have essential difficulties for applications to equipment and materials for entertainment, for example.